When inserting a catheter into a living body lumen such as a digestive tract and a blood vessel, a guide wire is used in order to guide the catheter to a target site of the living body lumen. The guide wire is used by being inserted into the catheter. In addition, observation or treatment of the living body lumen is also performed by using an endoscope, and thus the guide wire is used in order to guide the catheter inserted into the endoscope or a lumen of the endoscope to the target site of the living body lumen.
A guide wire is known which has an elongated wire body, a resin coating layer for covering a distal portion of the wire body and an annular member arranged on a proximal side of the resin coating layer. Such a conventional guide wire has a problem, however, in that when a distal portion of the guide wire is curved with a comparatively small radius of curvature, the proximal end of the resin coating layer and the distal end of the annular member may be separated from each other, thus producing a crack in the boundary between them. Specifically, the proximal portion of the resin coating layer may peel away from the wire body and may turn up. Thus, when the catheter is pushed in along the guide wire from a proximal end of the guide wire, a distal end of the catheter may be caught on the turned-up part of the guide wire.
Guide wires disclosed in JP-A-2008-307367 and WO 2011/118443, for example, prevent turning up of the resin coating layer by defining a proximal outer diameter of the resin coating layer and a distal outer diameter of the annular member. It has been found however that further modifications are required to prevent turning up of the guide wire and thereby improve operability.